Removal of metal ions by means of solar oxidation processes based on pH, TiO_2 and oxidants

摘要

The present study is targeted at the feasibility of photocatalytic treatment of wastewater containing metal ions. The relatively newest of which is photo catalysis with titanium dioxide which may also be used, plus hydrogen peroxide as a hole scavenger to improve the treatment rate. In this study, photocatalysis/ hydrogen peroxide processes had been employed for the removal of four metal ions Cr, Cu, Ni, and Zn present in the wastewater. Experiments were carried out to find an optimum dose of H_2O_2, used as hole scavenger. The absorption and reduction of the metal ions at different pH values (7.2, 2, 4, 6, 8 and 10) were also investigated. The detention time was kept constant (300 min). Results indicated that at pH 2, complete reduction was achieved for Cr. However, Cu, and Zn reduced completely even at alkaline and natural pH in a minimum time period; and 94.8% reduction of Ni at the alkaline pH was obtained by solar radiation. On the other side without solar radiation, the percentage of removal of metals are very less.